1. Field of the Invention
The abovementioned invention relates to a method, with which it is possible to drive impression cylinder receiving carriages into the printing elements automatically.
2. Description of Related Art
It is known that rotary printing machines consist of a series of printing elements which are arranged with mutual spacing and are fitted with known mechanical equipment which allows the web of paper to be printed to be moved through a multiplicity of successively arranged printing elements. Each of these printing elements has in a known manner a pressing roller which has the task of pressing the web of paper against an impression cylinder. Each impression cylinder is mounted in its own receiving carriage and each receiving carriage has a known squeegee device and an ink application device.
It is known that, when the printing programme is changed if, for example, a change is made from printing a particular product to printing a different product, it is necessary to stop the rotary printing machine in order to allow the individual impression cylinder receiving carriages to be driven out of the printing elements. Subsequently, the impression cylinder receiving carriages which are no longer to be used must be transported away from the associated printing element and only then is it possible to drive new impression cylinder receiving carriages into the gaps provided between the printing elements in order subsequently to drive the receiving carriages with the new cylinders into the printing units in order to start up the printing operation of the new product after carrying out the operations previously described.
Considering the fact that the investments to be made for a printing machine are very great, it is understandable that a printing works will strive to reduce the stoppage times of the machine to a minimum, that is to say those stoppage times required for exchanging the impression cylinder receiving carriages, an operation which even today is still largely carried out by hand.
An apparatus has been disclosed by the prior art, in which a transporting device is provided coaxially with the printing elements, on which transporting device the impression cylinder receiving carriages are arranged in order to drive the carriages from a waiting position into the gap between two printing elements in each case and subsequently to drive the corresponding impression cylinder receiving carriage into the printing element.
If the impression cylinders are to be exchanged by new cylinders, the cylinders are pushed through the individual printing units in order to occupy the adjacent gap between two printing elements and subsequently deposited on the transporting device again by a transverse movement.
This known apparatus has the disadvantage that it is necessary to provide a deep channel in the longitudinal direction of the rotary printing machine, which channel is suitable for receiving the components for the transporting device of the impression cylinder receiving carriages.
The necessity of providing a channel which extends over the entire length of the rotary printing machine entails considerable disadvantages and often cannot be accomplished for technical reasons, for example if the rotary printing machine is mounted on a floor which may not be changed.
A rotary printing machine has also been disclosed, in which the attempt has been made to reduce the stoppage times for exchanging the impression cylinder receiving carriages by providing for each printing element a twin-design impression cylinder receiving carriage, that is to say a receiving carriage which is constructed for receiving two impression cylinders, two squeegee devices and two corresponding ink application devices.
The disadvantage of this embodiment is to be seen in the fact that, for driving an impression cylinder receiving carriage of double width into the gap between two printing elements, said gap must be doubled in its dimensions, which leads to the overall length of the rotary printing machine increasing in an undesirable manner.
Furthermore, when using receiving carriages for two impression cylinders, a certain inertia is found in the displacement movement, which inertia does not allow the impression cylinder receiving carriage which is just in the waiting position to be exchanged, if required, by another impression cylinder receiving carriage which is fitted with a different impression cylinder.
A further disadvantage is to be seen in the fact that the receiving carriages for two impression cylinders are very heavy and consequently a great amount of force is required for moving these impression cylinder receiving carriages.